Electrical condenser



Feb. 24,1942. -rRK 2,274,011

ELECTRICAL CONDENSER Filed July 27, 1937 Patented Feb. 24, 1 942 UNITEDSTATES. PATENT, OFFICE ELECTRICAL CONDENSER Hermann Strib, Stuttgart,Germany, assignmto Robert Bosch Gesellschaft mit beschrinkter Haftung,Stuttgart, Germany Application July 27, 1937, Serial No. 156,023 InGermany August 5, 1936 6 Claims.

The invention relates to improvements inflat pack or pressedelectrostatic wound condensers,

particularly to those having a very thin metal denser in such a way thatthe metal coating of the condenser is allowed to project up to the frontof the wound condenser or beyond it and a metal layer-is applied to thefront, for instance, by spraying by the Schoop spraying process. Aconnecting wire can be soldered on to this metal layer. In order toobtained a good adhesion of the current connecting layer on to the metalcoating of the condenser, it is useful to apply the current connectionlayers before impregnating the wound condenser. In order that afterapplying the metal layer, the impregnating medium may penetrate into thecondenser, it is advantageous not to provide the whole front of thecondenser with a metal layer, but only one or several parts of its frontside.

Now it has been discovered that a flat pressed wound condenser thecurrent connections of which are produced in the manner indicated mayunder certain circumstance have a greatly reduced puncture strength whenthe metal layer is applied to those parts of the inner condenserwindings that have been bent during pressing. This is explained by thefact that the impregnating agent cannot penetrate into those parts ofthe. front of the condenser to which the metal layer is applied;Therefore the parts of the condenser under the metal layers applied tothe front sides are not as fully provided with the impregnating agent asthe other parts, since there is a longer way for the impregnating agentto .reach these parts than if it could penetrate di- The.

rectly on the front side of the condenser. parts of the condensersituated under the metal layer have consequently a somewhatsmaller vpuncture strength than the other points.

In order to keep the reduction of the disrup tive strength so producedas small as possiole, according to this invention the parts of the woundbands bent during the flat pressing of the wound condenser are kept freefrom the current connection layer at least within the first inner thirdof the winding bands on the front of the condenser.

These bent parts are, of course, con

siderabiy stressed by the mechanical .tensile stresses which haveoccurred during the fiat pressing. It is consequently'doubly importantthat these parts should be adequately impregnated. I

The invention is more particularly described with reference to theaccompanying drawing,. in which:

Figure 1 is an elevation of one form of con- .struction.

0, d, and f, metal layers are sprayed on, ,on to which a currentconnection wire g is soldered. The regions a and b are left free fromthe metal layers.

The metal layers 0 and d are situated on the front faces of the outercondenser windings, and

these, on being pressed flat are not so sharply bent as the innerwindings. In order to provide a current lead for the inner windings fromthe front faces of the condenser, a further metal layer 1 is providedbetween the two bent places It and i of the innermost winding; thismetal layer here covers the front faces of the inner windings which havebeen left free from the layers 0 and d at the bent parts.

Instead of the metal layers c and d being applied at the rounded ofiparts of the condenser they may also be arranged between the points hand i'and united with the metal layer 1. How- .ever, this arrangementhas the dis-advantage,

puncture disappears in a region which is'larger than the hole in thedielectric, whereby the short circuit current is by itself interrupted.In this process there occur very small quantities of gas which cause aslight swelling of the condenser. This swelling occurs particularly inthose regions of the wound condenser where the windings lie flat. withthis swelling there is a certain possibility that the sprayed-on metallayers will burst.

By the arrangement described this danger is reduced to the lowestpossible degree.

I declare that what I claim is:

1. An electric wound condenser of the fiat type comprising flat stripwinding coiled upon them-.

. themselves, a dielectric separating the conducting metal coatings ofthe condenser, said metal coatings of different potential vice versaprojecting one on each front side of the condenser and one or morecoherent layers of metal applied on the front sides electricallyconnected to the projecting edges of the coatings whereby at least thefirst inner thirds of the bent parts of the windings are kept free fromsaid metal layers.

3. An electric wound condenser of the flat type comprising flat stripwindings coiled upon themselves, a dielectric separating the conductingmetal coatings of the condenser, said metal coatings of differentpotential vice versa projecting one on each front side of the condenserand. one or more coherent layers of metal applied on the front sideselectrically connected to the projecting edges of the coatings wherebyat least the first inner thirds of the bent parts of the windings arekept free from saidmetal layers and a metal wire conductor soldered tosaid applied metal layers, each conductor electrically connecting all ofthe applied metal layers on each side of said condenser, but beingspaced from said windings.

4. An electric wound condenser of the flat type comprising fiat stripwindings coiled upon themselves, a dielectric separating the conductingmetal coatings of the condenser, said metal coatings of difierentpotential vice versa. projecting one on each front side of the condenserand at least three coherent layers of metal applied on the front sideselectrically connected to the projecting edges of the coatings wherebythe contact metal layers of the inner windings of the condenser areapplied between the two bending points of theinnermost winding and thoseof the outer windings on one or on each rounded part of the front sidesof ,the condenser, the inner bent parts of the windings being free fromsaid metal layers.

5. An electric wound condenser of the fiattype comprising flat stripwindings coiled upon themselves, a dielectric separating the conductingmetal coatings of the condenser, said metal coatings of differentpotential vice versa projecting one on each front side of the condenserand at least three coherent layers of metal applied on the front sideselectrically connected to the projecting edges of the coatings wherebythe contact metal layers of the inner windings of the condenser areapplied between the two bending points of the innermost winding andthose of the outer windings'on one or each rounded part of the frontsides of the condenser and a metal wire conductor soldered to saidapplied metal layers, the inner bent parts of the windings being freefrom said metal layers, each conductor electrically connecting all ofthe applied metal layers on each side of said condenser, but beingspaced from said windings.

6. An electric wound condenser of the flat type comprising fiat stripwindings of metal and-insulating material coiled upon themselves toprovide successive layers of metal and insulating material, alternatelayers of metal being exposed at opposite sides, respectively, of saidcondenser. and a layer of metal applied to the edges of said windings ateach side of said condenser to electrically connect metal layers of likepolarity, the inner bent edges of said windings being free from saidapplied metal layers.

HERMANN sTRAB.

